Remove duplicate CSS in dev (#5917)

* fix(#5817): remove duplicate CSS in dev

* chore: add changeset

Co-authored-by: Nate Moore <nate@astro.build>

Author: natemoo-re

.changeset/rotten-cups-happen.md

@@ -0,0 +1,5 @@
+---
+'astro': patch
+---
+
+Fix duplicate CSS in dev mode when `vite.css.devSourcemap` is provided

packages/astro/e2e/css-sourcemaps.test.js

@@ -0,0 +1,38 @@
+import { expect } from '@playwright/test';
+import { getColor, isWindows, testFactory } from './test-utils.js';
+
+const test = testFactory({
+	root: './fixtures/css/',
+});
+
+let devServer;
+
+test.beforeAll(async ({ astro }) => {
+	devServer = await astro.startDevServer();
+});
+
+test.afterAll(async () => {
+	await devServer.stop();
+});
+
+test.describe('CSS Sourcemap HMR', () => {
+	test.skip(isWindows, 'TODO: fix css hmr in windows');
+
+	test('removes Astro-injected CSS once Vite-injected CSS loads', async ({ page, astro }) => {
+		const html = await astro.fetch('/').then(res => res.text());
+		
+		// style[data-astro-dev-id] should exist in initial SSR'd markup
+		expect(html).toMatch('data-astro-dev-id');
+
+		await page.goto(astro.resolveUrl('/'));
+
+		// Ensure JS has initialized
+		await page.waitForTimeout(500);
+
+		// style[data-astro-dev-id] should NOT exist once JS runs
+		expect(await page.locator('style[data-astro-dev-id]').count()).toEqual(0);
+
+		// style[data-vite-dev-id] should exist now
+		expect(await page.locator('style[data-vite-dev-id]').count()).toBeGreaterThan(0);
+	});
+});

packages/astro/e2e/css.test.js

@@ -30,4 +30,22 @@ test.describe('CSS HMR', () => {
 
 		expect(await getColor(h)).toBe('rgb(0, 128, 0)');
 	});
+
+	test('removes Astro-injected CSS once Vite-injected CSS loads', async ({ page, astro }) => {
+		const html = await astro.fetch('/').then(res => res.text());
+		
+		// style[data-astro-dev-id] should exist in initial SSR'd markup
+		expect(html).toMatch('data-astro-dev-id');
+
+		await page.goto(astro.resolveUrl('/'));
+
+		// Ensure JS has initialized
+		await page.waitForTimeout(500);
+
+		// style[data-astro-dev-id] should NOT exist once JS runs
+		expect(await page.locator('style[data-astro-dev-id]').count()).toEqual(0);
+
+		// style[data-vite-dev-id] should exist now
+		expect(await page.locator('style[data-vite-dev-id]').count()).toBeGreaterThan(0);
+	});
 });

packages/astro/e2e/fixtures/css-sourcemaps/astro.config.mjs

@@ -0,0 +1,7 @@
+export default {
+	vite: {
+		css: {
+			devSourcemap: true,
+		}
+	}
+};

packages/astro/e2e/fixtures/css-sourcemaps/package.json

@@ -0,0 +1,8 @@
+{
+  "name": "@e2e/css-sourcemaps",
+  "version": "0.0.0",
+  "private": true,
+  "dependencies": {
+    "astro": "workspace:*"
+  }
+}

packages/astro/e2e/fixtures/css-sourcemaps/src/env.d.ts

@@ -0,0 +1 @@
+/// <reference types="astro/client" />

packages/astro/e2e/fixtures/css-sourcemaps/src/pages/index.astro

@@ -0,0 +1,9 @@
+<h1>hello world</h1>
+
+<style>
+  @import "../styles/main.css";
+
+  h1 {
+    color: var(--h1-color);
+  }
+</style>

packages/astro/e2e/fixtures/css-sourcemaps/src/styles/main.css

@@ -0,0 +1,3 @@
+:root {
+  --h1-color: red;
+}

packages/astro/src/core/render/dev/index.ts

@@ -10,7 +10,7 @@ import { PAGE_SCRIPT_ID } from '../../../vite-plugin-scripts/index.js';
 import { enhanceViteSSRError } from '../../errors/dev/index.js';
 import { AggregateError, CSSError, MarkdownError } from '../../errors/index.js';
 import type { ModuleLoader } from '../../module-loader/index';
-import { isPage, resolveIdToUrl } from '../../util.js';
+import { isPage, resolveIdToUrl, viteID } from '../../util.js';
 import { createRenderContext, renderPage as coreRenderPage } from '../index.js';
 import { filterFoundRenderers, loadRenderer } from '../renderer.js';
 import { getStylesForURL } from './css.js';
@@ -133,7 +133,11 @@ async function getScriptsAndStyles({ env, filePath }: GetScriptsAndStylesParams)
 		});
 		// But we still want to inject the styles to avoid FOUC
 		styles.add({
-			props: {},
+			props: {
+				type: 'text/css',
+				// Track the ID so we can match it to Vite's injected style later
+				'data-astro-dev-id': viteID(new URL(`.${url}`, env.settings.config.root))
+			},
 			children: content,
 		});
 	});

packages/astro/src/runtime/client/hmr.ts

@@ -1,15 +1,15 @@
 /// <reference types="vite/client" />
 
 if (import.meta.hot) {
-	// Vite injects `<style type="text/css">` for ESM imports of styles
-	// but Astro also SSRs with `<style>` blocks. This MutationObserver
+	// Vite injects `<style type="text/css" data-vite-dev-id>` for ESM imports of styles
+	// but Astro also SSRs with `<style type="text/css" data-astro-dev-id>` blocks. This MutationObserver
 	// removes any duplicates as soon as they are hydrated client-side.
 	const injectedStyles = getInjectedStyles();
 	const mo = new MutationObserver((records) => {
 		for (const record of records) {
 			for (const node of record.addedNodes) {
 				if (isViteInjectedStyle(node)) {
-					injectedStyles.get(node.innerHTML.trim())?.remove();
+					injectedStyles.get(node.getAttribute('data-vite-dev-id')!)?.remove();
 				}
 			}
 		}
@@ -31,8 +31,8 @@ if (import.meta.hot) {
 
 function getInjectedStyles() {
 	const injectedStyles = new Map<string, Element>();
-	document.querySelectorAll<HTMLStyleElement>('style').forEach((el) => {
-		injectedStyles.set(el.innerHTML.trim(), el);
+	document.querySelectorAll<HTMLStyleElement>('style[data-astro-dev-id]').forEach((el) => {
+		injectedStyles.set(el.getAttribute('data-astro-dev-id')!, el);
 	});
 	return injectedStyles;
 }
@@ -42,5 +42,5 @@ function isStyle(node: Node): node is HTMLStyleElement {
 }
 
 function isViteInjectedStyle(node: Node): node is HTMLStyleElement {
-	return isStyle(node) && node.getAttribute('type') === 'text/css';
+	return isStyle(node) && node.getAttribute('type') === 'text/css' && !!node.getAttribute('data-vite-dev-id');
 }